In circuit board design, a magnetic bead is indicated by an inductor in terms of circuit symbol, i.e., the magnetic bead is the inductor. Magnetic bead has a small inductance value, is easy to manufacture, and possesses some other characteristics that cannot be achieved in many conventional inductors. For example, a conventional inductor may be equivalent to a capacitance under high frequency (especially high order harmonic) in view of distributed capacitance, so that it cannot function as an inductor.
However, the magnetic bead does not have the above-mentioned defects of the conventional inductor. The magnetic bead has excellent high frequency characteristic, and stable inductance characteristic under high frequency. Therefore, as shown in FIG. 1, one or more magnetic beads (for example, a magnetic bead L1 and a magnetic bead L2) will be generally disposed at the locations, such as a power source end or the like, in the circuit design, no as to better remove clutters and restrain noise and pulse disturbance in a power line. However, the utilization of the magnetic beads, although removes the noise, results in an overlarge circuit board, thus increasing the production cost of the circuit board.